Surface pad system for a surgical table

ABSTRACT

A surface pad system for a surgical table includes a cover defining an interior region and including an upwardly-facing top surface configured to be positioned beneath a patient. The surface pad system also includes a pad core received in the interior region of the cover to support the patient.

This application is a continuation of U.S. application Ser. No.09/270,388, filed Mar. 16, 1999 now U.S. Pat. No. 6,182,316, which is adivisional of U.S. application Ser. No. 08/691,573, filed Aug. 2, 1996,now U.S. Pat. No. 5,966,763.

BACKGROUND SUMMARY OF THE INVENTION

The present invention relates to a surgical table for use in a hospitaloperating room, and particularly to a surface pad system for a surgicaltable, the surface pad system being carried by a generally horizontalupwardly-facing table-top surface of the surgical table and beingpositioned to lie beneath the patient. More particularly, the presentinvention relates to a surface pad system that can regulate thetemperature of the patient, assist in positioning the patient, and thatminimizes the interface pressure between the patient and apatient-support surface of the surface pad system thereby minimizing theoccurrence of pressure ulcers and neuropathy caused by prolongedexposure of the patient to high interface pressures between the patientand the patient-support surface.

It is known to provide surface covers for operating tables forsupporting patients above a table-top surface of the surgical table.Conventional surface covers typically include a foam rubber coresurrounded by ticking material. It is also known to provide a gel padbetween the foam rubber and a top panel of the ticking material coveringthe foam rubber. In addition, these operating table surface covers aretypically provided in the form of a set of pads including a head padsupporting the head of the patient, a body pad supporting the torso ofthe patient, and a foot pad supporting the lower legs and feet of thepatient. Occasionally, these sets include a fourth pad positionedlongitudinally between the body pad and the foot pad and supporting thesacrum of the patient.

It is also known to provide a patient support having an upwardly-facingtop surface, the temperature of which is controlled. For example, U.S.Pat. No. 5,402,542 to Viard, which is assigned to the assignee of thepresent invention, discloses a fluidized patient support having atemperature-controlled top surface supporting the patient.

It is also known to provide inflatable bladders and inflatable cushionsin mattresses which can be inflated and deflated to assist a caregiverwhen turning a patient relative to the sleeping surface of the mattress.For example, U.S. Pat. No. 5,269,0302 Pahno et al. discloses anapparatus and method for managing waste for patient care, the apparatusincluding inflatable sacks which assist turning the patient tofacilitate cleansing of the patent. In addition, U.S. Pat. Nos.4,949,414 and 5,062,167 to Thomas et al., which are assigned to theassignee of the present invention, disclose a bi-modal turning methodthat utilizes a mattress including a plurality of identicalmulti-chambered inflatable sacks.

What is needed is a surface pad system for a surgical table that canassist with the regulation of the temperature of the patient on thepatient-support surface, that can position the patient, and thatminimizes the interface pressure at high pressure points between thepatient and the patient-support surface. The patient-support surface ofthe surface pad system should be conformable to fit the contours of thepatient and maximize the surface area of contact between thepatient-support surface and the patient, thereby minimizing theinterface pressure between the patient and the patient-support surface.

The surface pad system should also be capable of moving or rolling thepatient from an initial position to a new position without requiring themembers of the surgical team to reposition the anesthetized patient andwithout requiring the members of the surgical team to stuff pillows,towels, wedges, or other objects between the patient and thepatient-support surface while manually holding the patient in the newposition to keep the patient in the new position after the members ofthe surgical team stop holding the patient. In addition, once thepatient is moved to the new position, the surface pad system shouldrigidly support the patient in the desired position. Finally, thepatient-support system should maintain the patient at a comfortabletemperature while the patient is awake, and once anesthetized, thepatient-support system should assist in reducing the temperature of thepatient to the desired operating temperature selected by the surgicalteam.

According to the present invention, a surface pad system is provided fora surgical table. The surface pad system includes a cover having anupwardly-facing patient-support surface, the cover defining an interiorregion of the surface pad system. A vacuum bead bag is received in theinterior region of the surface pad system. The vacuum bead bag includesa flexible cover defining an interior region containing compressiblebeads. A bladder is received in the interior region of the cover and ispositioned to lie beneath the vacuum bead bag. The bladder defines aninterior region of the bladder and is inflatable when pressurized fluidis received in the interior region so that the vacuum bead bagconformingly engages the patient on the patient-support surface when thebladder is inflated.

In preferred embodiments the surface pad system includes a plurality ofpad sections that are positioned to lie on the upwardly-facing table-topof a surgical table between the patient and the surgical table. Thepreferred surface pad system includes a head pad section positioned tolie beneath the head of the patient, a leg pad section longitudinallyspaced apart from the head pad section and positioned to lie beneath thelower legs and feet of the patient, a body pad section positioned to liebetween the head pad section and the leg pad section, and first andsecond arm pad sections each of which is positioned to lie beside thebody pad section and beneath an arm of the patient.

Each pad section of the surface pad system includes a pad core receivedby a cover of the pad section. Each pad core includes a plurality of padcore elements. Preferably, each pad core includes a base foam supportlayer made from high density foam that is positioned to lie beneath theother pad core elements and that provides a structural foundation forthe pad core.

Each preferred pad core also includes a bladder pad having one or morebladders in fluid communication with a pressurized fluid source andinflatable to a first pressure for pressing the patient-support surfaceagainst the patient to conform to the shape of the patient when thebladders are inflated to the first pressure. In addition, selectedbladders can be inflated to a second pressure which is greater than thefirst pressure. Each selected bladder can be arranged relative to thepad section so that when the bladder is inflated to the second pressure,the bladder and the patient support surface reposition the patient froman initial position to a new position by raising the portion of thepatient-support surface above the bladder from its initial position to ahigher position and repositioning the patient, for example, by causingthe patient to tilt or roll away from the bladder. If desired, thebladder can be subsequently deflated to reduce the pressure in thebladder to the first pressure and causing the patient to move back tothe initial position.

Also, each preferred pad section includes a vacuum bead bag which ispreferably positioned to lie on top of the bladder pad. The vacuum beadbag includes a casing forming an interior region containing a pluralityof tubes, each of which is filled with compressible beads. The interiorregion of the vacuum bead bag is in fluid communication with a vacuumsource. When air is evacuated from the interior region of the vacuumbead bag, the compressible beads are compressed against one another anddeform so that the beads are held immobile with respect to one anotherand the vacuum bead bag rigidly assumes the shape that it is in when theinterior region is evacuated.

The vacuum bead bag in accordance with the present invention includes anupper layer of elongated tubes containing compressible beads and a lowerlayer of elongated tubes containing compressible beads. Each tube in thelower layer of the vacuum bead bag extends in a first direction. Eachtube in the upper layer of the vacuum bead bag extends in a seconddirection. The second direction is different from the first direction,and preferably the second direction is generally perpendicular to thefirst direction. This “plywood” arrangement provides an extremely rigidsupport when the interior region of the vacuum bead bag is evacuated. Bylayering the tubes in the criss-crossing plywood arrangement with“grains” of each layer running in generally perpendicular directionprovides support for the patient both in a longitudinal direction and ina lateral direction.

Each pad section of the surface pad system also preferably includes apressure-reduction foam layer made from foam rubber which is positionedto lie on top of the vacuum bead bag. The pressure-reduction foam layeris made from a thermally active “visco-elastic” foam rubber material.When the foam layer is at a warmer temperature the foam is softer andmore pliable and when the foam layer is at a cooler temperature the foamis harder and retains its shape.

When a patient is awake and the patient-support surface in maintained ata comfortable warm temperature, the visco-elastic pressure-reductionfoam layer will tend to conform to the shape of the patient. After thepatient is anesthetized and the temperature of the patient-supportsurface is lowered, the visco-elastic pressure-reduction foam layer willtend to retain its shape. Thus, if the position of the patient ischanged during the course of a surgical procedure, once the patient ismoved back into his or her original position, the pressure-reductionfoam layer will have generally retained its original shape and thus willbe shaped to receive the patient.

Each pad section of the surface pad system also includes a thermal padwhich is preferably positioned to lie above the pressure-reduction foamlayer. The thermal pad is positioned to lie above the pressure-reductionfoam layer to maximize the effectiveness of the heat transfer betweenthe thermal pad and the patient-support surface and to minimize theimpact of the thermally insulating pressure-reduction foam layer on theheat transfer between the thermal pad and the patient-support surface.

The thermal pad includes a serpentine-shaped channel defined therein. Athermoregulation fluid is received in the channel and is circulatedthrough the channel to maintain the temperature of the thermal pad andthus maintain the temperature of the patient-support surface near thetemperature of the thermoregulation fluid. The channel is in fluidcommunication with a heat exchanger so that the temperature of thethermoregulation fluid, and thus the temperature of the patient-supportsurface, can be adjusted according to the desires of the surgical teamby using the heat exchanger to adjust the temperature of thethermoregulation fluid flowing through the channel.

A gel pack is positioned to lie on top of the thermal pad. The gel packincludes a casing containing a viscous material such as a siliconpolymer of the type used to produce prosthetic devices. The viscousmaterial will tend to flow away from high interface pressure points andwill tend to flow toward low interface pressure points, thus more evenlydistributing the weight of the patient and buoying the patient away fromthe high interface pressure points, thereby minimizing the interfacepressure between the patient and the patient-support surface at the highinterface pressure points. Preferably, a thermocouple is positionedwithin the gel in the gel pack to provide feedback to the heat exchangercontrolling the temperature of the thermoregulation fluid.

A cut-proof material is positioned to lie above the gel layer. Thecut-proof material operates to protect the pad core, and particularlythe gel layer, the thermal pad, and the bladder from puncture due todropped scalpels, dropped needles, or other sharp objects. In addition,the cut-proof material is preferably placed along the sides of each padsection to provide additional protection against punctures and cuts.

The cover is formed to include an interior region surrounding the padcore and holding the pad core elements in place relative to one another.Preferably, the cover is made from a bi-directional stretch materialthat can be stretched both in a longitudinal direction and in a lateraldirection. Use of a bidirectional stretch material eliminates folding ofthe cover material on itself during movement of portions of each padsection relative to other portions of each pad section. In addition, thecover is preferably made from a liquid impermeable material to bothprotect the pad core elements from exposure to fluids from outside ofthe cover and to protect the patient from exposure to fluids from thepad core elements in the event of rupture of the gel pack, the thermalpad, or one of the bladders. If desired, a fire proof sock can bepositioned to lie between the pad core elements and the cover to assistwith extinguishing flames after the pad core elements are exposed toflames, a characteristic required by regulations imposed by severalregulating authorities.

The pad sections can be configured so that each pad section couples toeach other pad section. For example, the head pad section can be coupledto the body pad section and the body pad section can be coupled to theleg pad section and both of the arm pad sections. Preferably, thechannels formed in the thermal pads of each pad section are in fluidcommunication with one another so that the thermoregulation fluidcirculates through the thermal pads of each pad section. Circulating thethermoregulation fluid through the thermal pad of each pad sectionallows for the temperature of the thermoregulation fluid to be regulatedby a single heat exchanger rather than including a separate heatexchanger for the thermal pad of each pad section.

Likewise, the vacuum bead bag of each pad section can be in fluidcommunication with the vacuum bead bag of each other pad section. Thiscoupling permits the use of only one vacuum source which is used tooperate the vacuum bead bags of each pad section. Also, although thebladders in each of the pad sections are not in fluid communication withone another, the bladder pad in each pad section is formed to include aninternally contained channel system eliminating the need to includehoses connected to each bladder. The channel system allows for the useof a single pressurized fluid source which can inflate and deflate thebladders of each pad section.

A controller is provided for the surface pad system in accordance withthe present invention. The controller is used to control the operationof the heat exchanger, the vacuum source, and the pressurized fluidsource. The use of a single controller to control each of the heatexchanger, the vacuum source, and the pressurized fluid source allowsfor the coordination of each of these systems. For example, thecontroller can be programmed to lower the temperature of thepatient-support surface during surgical procedures at a predeterminedcooling rate. However, if desired, the lowering of the temperature canbe programmed to occur only after the bladders are inflated and afterair is evacuated from the vacuum bead bags. In addition, a“chest-expanding” bladder can be provided in the body pad section whichcan be pressurized to hyperextend the chest cavity of a patient duringsurgical procedures. If desired, the controller can be programmed toallow this inflation of the chest-expanding bladder only after thetemperature of the patient-support surface has been lowered to thedesired operating temperature by the thermoregulation fluid in thethermal pad.

Additional objects, features, and advantages of the invention willbecome apparent to those skilled in the art upon consideration of thefollowing detailed description of a preferred embodiment exemplifyingthe best mode of carrying out the invention as presently perceived.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description particularly refers to the accompanying figuresin which:

FIG. 1 is a perspective view of a surface pad system in accordance withthe present invention with portions broken away showing a plurality ofpad sections and a control unit positioned to lie adjacent to the headend of the surface pad system, the control unit providing pressurizedfluid, vacuum, and a temperature-controlled thermoregulation fluid tothe pad sections, a head pad section adjacent to a head end of thesurface pad system, a leg pad section longitudinally spaced-apart fromthe head pad section and positioned to lie near a foot end of thesurface pad system, a body pad section positioned to lie between thehead pad section and the leg pad section, the body pad section havingfirst and second spaced-apart elongated sides, first and second arm padsections positioned to lie adjacent to the first and second sides of thebody pad section, respectively, conduits connecting the head, body, leg,and arm pad sections for flowing thermoregulation fluid therebetween,and additional conduits connecting the head, body, and leg pad sectionsto one another for flowing pressurized fluid and vacuum therebetween;

FIG. 2 is a sectional view taken along line 2—2 of FIG. 1 showing aconcave top surface of the arm pad section, the arm pad sectionincluding a base foam portion made from high density foam, a thermal padformed to include a channel through which thermoregulation fluid flows,the thermal pad being positioned to lie on top of the base foam layer,and a gel pack positioned on top of the thermal pad, the gel packincluding a casing containing viscous fluid which flows within thecasing to minimize the interface pressure between the patient and thetop surface of the arm section;

FIG. 3 is a side view with portions broken away of the body pad sectionshowing a cover defining an interior region of the body pad section, theinterior region receiving a base foam support layer made from highdensity foam, a bladder pad positioned to lie on top of the base foamlayer, a vacuum bead pad positioned to lie on top of the bladder pad andincluding a plurality of tubes containing compressible beads, theplurality of tubes defining an upper layer of tubes extending in alongitudinal first direction and a lower layer of tubes extending in atransverse second direction which is generally perpendicular to thefirst direction, an upper foam layer positioned to lie on top of thevacuum bead bag, a thermal pad positioned to lie on top of the upperfoam layer, and a gel pack sandwiched between the thermal pad and thecover;

FIG. 4a is an exploded perspective view of the body pad section of thesurface pad system of FIG. 1 showing a cover made from ticking materialand defining an interior region of the cover receiving a pad coreincluding the base foam support layer positioned beneath the bladderpad, and the vacuum bead bag, the upper foam layer, the thermal pad, andthe gel pack, all of which are positioned above the bladder pad;

FIG. 4b is a view of the underside of the vacuum bead bag of FIG. 4ashowing that longitudinally-extending tubes of compressible beads arepositioned to lie beneath the transversely-extending tubes ofcompressible beads to produce a “plywood” effect;

FIG. 4c is a view of the underside of the bladder pad of FIG. 4a showingthat the bladder pad is an integral pad formed to include channels onthe underside of the bladder pad beneath the bladders on the upper sideof the bladder pad;

FIG. 5 is a sectional view taken along line 5—5 of FIG. 1 showing thebody pad section of the surface pad system, a person lying on apatient-support surface of the surface pad system, and gaps formedbetween the patient-support surface and the patient;

FIG. 6 is a view similar to FIG. 5 of the surface pad system after thebladders have been inflated and expanded showing the patient-supportsurface pressed against the patient by the bladders and conforming tothe shape of the patient to maximize the surface area of contact betweenthe patient and the patient-support surface and thereby more evenlydistribute the weight of the patient across the patient-support surface;

FIG. 7 is an enlarged view of a portion of FIG. 6 showing the vacuumbead bag after air has been evacuated from the interior region of thevacuum bead bag so that the compressible beads have deformed against oneanother to become immobile relative to one another so that the vacuumbead bag is rigid and retains the shape that it attained prior to havingthe air evacuated from the interior region of the vacuum bead bag;

FIG. 8 is a view similar to FIG. 6 showing the surface pad system afterthe air has been evacuated from the interior region of the vacuum beadbag and after the bladders have been deflated so that the now rigidvacuum bead bag causes the patient-support surface to retain the shapeconforming to the shape of the patient resting on top of thepatient-support surface while allowing the bladders to be deflated toreduce the resiliency of the surface pad system so that the patient isfirmly supported by the table to minimize the vibration and bouncingmovement of the patient during surgical procedures;

FIG. 9 is a view similar to FIG. 8 showing a double bladder on one sideof the patient that is inflated to tilt the patient away from the doublebladder, the vacuum bead bag causing the patient-support surface toconform to the shape of the patient, gripping the patient to preventsliding of the patient when the patient-support surface is tilted;

FIG. 10 is a view similar to FIG. 6 showing a central bladder on thebladder pad which is inflated to hyperextend the chest cavity of thepatient;

FIG. 11 is a view similar to FIG. 6 showing a pocket formed on a bottomsurface of the cover and receiving a separate bladder that is not partof the bladder pad and that can be inflated to tilt the pad section andthe patient-support surface;

FIG. 12 is a diagrammatic view of a patient lying on the patient-supportsurface showing the positions of the bladders (in phantom) ofillustrative surface pad system beneath the patient;

FIG. 13a is a diagrammatic view illustrating the uneven interfacepressure distribution of a patient resting on a conventional surfacecover for a surgical table;

FIG. 13b is a diagrammatic view similar to FIG. 13a illustrating theinterface pressure distribution of a patient resting on thepatient-support surface of the surface pad system in accordance with thepresent invention before any of the bladders are inflated and before airis evacuated from the vacuum bead bag;

FIG. 13c is a diagrammatic view similar to FIG. 13b showing theinterface pressure distribution between the patient and thepatient-support surface of the surface pad system in accordance with thepresent invention after the bladders have been inflated to cause thepatient-support surface to conform to the shape of the patientmaximizing the surface area of contact between the patient and thepatient-support surface and after air has been evacuated from the vacuumbean bags so that the weight of the patient is distributed more evenlyover the patient-support surface, thereby minimizing high interfacepressure points; and

FIG. 14 is a diagrammatic view of a control system of the surface padsystem showing the pad sections coupled to the control system includinga heat exchanger, a pressurized fluid source, a vacuum source, a keypad,thermocouples, and controller for communicating with and controlling theoperation of the other elements of the control system.

DETAILED DESCRIPTION OF THE DRAWINGS

A surface pad system 20 in accordance with the present inventionincludes a plurality of pad sections 30 carried by an upwardly-facingtable-top 22 of a surgical table as shown in FIG. 1. Table-top 22includes a head end 24, a foot end 26, a first side 38, and a secondside 40. As used in this description, the phrase “head end 24” will beused to denote the end of any referred-to object that is positioned tolie nearest the head end 24 of table-top 22 and the phrase “foot end 26”will be used to denote the end of any referred-to object that ispositioned to lie nearest foot end 26 of table-top 22. Likewise, thephrase “first side 38” will be used to denote the side of anyreferred-to object that is positioned to lie nearest first side 38 oftable-top 22 and the phrase “second side 40” will be used to denote theside of any referred-to object that is positioned to lie nearest secondside 40 of the table-top 22.

Surface pad system 20 includes a head pad section 32 positioned to lieon head end 24 of table-top 22, a leg pad section 36 longitudinallyspaced apart from head pad section 32 and positioned to lie on foot end26 of table-top 22, and a body pad section 34 positioned to lietherebetween as shown in FIG. 1. Surface pad system 20 further includesa first arm pad section 42 positioned to lie adjacent to first side 38of body pad section 34 and a second arm pad section 44 positioned to lieadjacent to second side 40 of body pad section 34.

Head pad section 32 is formed to include an upwardly-facing top surface46, body pad section 34 is formed to include an upwardly-facing topsurface 48, leg pad section 36 is formed to include an upwardly-facingtop surface 50, first arm pad section 42 is formed to include anupwardly-facing top surface 52, and second arm pad section 44 is formedto include an upwardly-facing top surface 54. Top surfaces 46, 48, 50,52, 54 are spaced apart from table-top 22 of the surgical table bygenerally equivalent distances and are generally coplanar so that topsurfaces 46, 48, 50, 52, 54 cooperate to define a generally horizontalupwardly-facing patient support surface 56 of surface pad system 20.

Pad sections 30 are connected to one another by conduits 60 including athermoregulation fluid supply conduit 62, a thermoregulation fluidreturn conduit 64, a pressurized fluid conduit 66, and a vacuum conduit68 as shown in FIG. 1 and as shown diagrammatically in FIG. 14.Thermoregulation fluid supply conduit 62 brings surface pad system 20into fluid communication with a heat exchanger 372 contained in acontrol housing 74 of surface pad system 20. Thermoregulation fluidreturn conduit 64 also brings surface pad system 20 into fluidcommunication with the source of thermoregulation fluid and returnconduit 64 cooperates with supply conduit 62 to circulatethermoregulation fluid through surface pad system 20.

Pressurized fluid conduit 66 brings surface pad system 20 into fluidcommunication with a source of pressurized fluid 374. The pressurizedfluid is preferably pressurized air, although the pressurized fluid caninclude pressurized water, pressurized treated water which is treated,for example, to have a viscosity greater than the viscosity of untreatedwater, or any other generally inert gaseous or liquid fluid that can beused as described below to operate surface pad system 20 without thescope of the invention as presently perceived.

Vacuum conduit 68 brings pad sections 30 of surface pad system 20 intofluid communication with a vacuum source 376. Vacuum source 376 can bemanipulated to evacuate air from desired portions of pad sections 30 asdescribed below and to allow air or any other selected gas that isgenerally inert to return to the evacuated portions of pad sections 30.

Each pad section 30 can be provided with cut-proof material 70 as shownin FIG. 1 to protect pad section 30 from puncture or penetration bydropped scalpels, dropped needles, or other sharp objects thatinadvertently contact pad sections 30. Preferably, cut-proof material 70is placed beneath patient-support surface 56 adjacent to sides 38, 40 ofpad sections 30 and along other portions of patient-support surface 56that are unlikely to be engaged by a patient resting on patient-supportsurface 56 but that might be susceptible to such damaging contact. Inaddition, cut-proof material 70 can be placed along generallyvertically-extending side walls of pad sections 30 for additionalprotection.

Surface pad system 20 also includes control housing 74 as shown in FIG.1, containing a controller 370 for controlling heat exchanger 372,source of pressurized fluid 374, and vacuum source 376, showndiagrammatically in FIG. 14. A key pad 378 is also carried by controlhousing 74 and is coupled to controller 370. Preferably, thethermoregulation fluid supply and return conduits 62, 64, thepressurized fluid conduit 66, and the vacuum conduit 68 all extend fromcontrol housing 74 to pad sections 30 through a single hose 76 as shownin FIG. 1. Preferably, hose 76 connects to surface pad system 20 nearhead end 24 of surface pad system 20 and adjacent to a needle receptacle78.

Needle receptacle 78 includes an outer shell 81 that is formed toinclude an opening which contains a medium 80 such as foam rubber, steelwool, or some other porous material that can receive needles. Needlereceptacle 78 provides a convenient storage location for anesthetistsand other surgical team members to store needles so that the surgicalteam members can store needles in needle receptacle 78 instead of usingpad sections 30 to store needles which presents the risk of puncturingpad sections 30.

Arm pad sections 42, 44 are pivotably coupled to body pad section 34 asshown in FIG. 1 so that arm pad sections 42, 44 can be pivoted away fromsides 38,40 of body pad section 34. Pivoting arm pad sections 42, 44away from sides 38, 40 of body pad section 34 provides members of thesurgical team with greater access to the patient carried onpatient-support surface 56.

In addition, top surfaces 52, 54 of first and second arm pad sections42, 44 each have a concave shape providing an elongated trough 82 whichcooperates with a pair of elongated outer ridges 84 to cradle the armsof the patient carried on patient-support surface 56. Thus, first andsecond arm pad sections 42, 44 lift the arms of the patient to aposition spaced apart above table-top 22 of the surgical table the samedistance that top surfaces 46, 48, 50 of head, body and leg pad sections32, 34, 36 are spaced apart from table-top 22, unlike some conventionalcoverings for surgical tables which allow the arms of the patient todangle beside the covering. In addition, ridges 84 cooperate with trough82 of top surfaces 52, 54 of arm pad sections 42, 44 to retain the armsof the patient on first and second arm pad sections 42, 44,respectively.

Each pad section 30 includes a cover 86 defining an interior region 88receiving a pad core 90 which includes a plurality of pad core elements92 as shown best in FIGS. 2-4a. For example, pad core 90 of illustrativesecond arm pad section 44 includes a high density foam base supportlayer 110, a thermal pad 260 engaging a top surface 112 of support layer110, a gel pack 310 positioned to lie on top of thermal pad 260, and afire sock 130 surrounding support layer 110, thermal pad 260, and gelpack 310 within interior region 88. Top surface 112 of support layer 110has a concave shape and is bowed downwardly so that top surface 54 ofsecond arm pad section 44 has the concave shape to cradle the arm of thepatient on patient-support surface 56. Thermal pad 260, gel pack 310,fire sock 130, and cover 86 generally conform to the shape of topsurface 112 of support layer 110 as shown in FIG. 2.

Although pad core 90 of illustrative second arm pad section 44 includesonly the pad core elements 92 of high density base foam support layer110, thermal pad 260, gel pack 310, and fire sock 130, other pad coreelements 92 can be added to pad core 90 without exceeding the scope ofthe invention as presently perceived as shown, for example, in FIGS. 3and 4a which show pad core elements 92 included in pad core 90 ofillustrative body pad section 34.

Pad core 90 of body pad section 34 illustratively includes high densitybase foam support layer 110 received in an interior region 132 of firesock 130 which is received in interior region 88 of cover 86. Supportlayer 110 engages fire sock 130 adjacent to a bottom 94 of cover 86 asshown in FIG. 3. A bladder pad 140 carrying bladders 146 for adjustingthe support and firmness characteristics of body pad section 34 isreceived in interior region 88 and is positioned to lie on top ofsupport layer 110. A vacuum bead bag 180 which can be manipulatedbetween a pliable state and a rigid state retaining its shape isreceived in interior region 88 and is positioned to lie on top ofbladder pad 140 and a pressure reduction foam layer 220 is received ininterior region 88 and is positioned to lie on top of vacuum bead bag180. Thermal pad 260 is received in interior region 88 and is positionedto lie on top of pressure reduction foam layer 220 and gel pack 310 isreceived in interior region 88 and is sandwiched between thermal pad 260and a top 96 of cover 86. Surface pad system 20 can thus include padsections 30 having pad core 90 including pad core elements 92 such asfire sock 130, support layer 110, bladder pad 140, vacuum bead bag 180,foam layer 220, thermal pad 260, and gel pack 310, or combinationsthereof, without exceeding the scope of the invention as presentlyperceived.

When a patient is initially placed on patient-support surface 56, theroom and patient-support surface 56 are typically warm to maximize thepatient's comfort so that the patient can relax. Support layer 110,pressure reduction foam layer 220, and gel pack 310 can deform somewhatto meet the contours of the patient's body, particularly at the warmertemperature. A member of the surgical team can use key pad 378 toprovide an instruction to controller 370 actuating bladder pad 140 andpushing patient-support surface 56 upwardly to even further conform tothe contours of the patient's body and minimize high interface pressurepoints between the patient and patient-support surface 56. Anothercommand can be provided to key pad 378 which causes vacuum bead bag 180to change from a pliable state to a rigid state retaining the shape thatvacuum bead bag 180 held when the command was provided. Once vacuum beadbag 180 is rigid, bladder pad 140 can be deactivated by providing acommand through key pad 378, without having patient-support surface 56lose its shape against the contours of the patient's body. Instead,rigid vacuum bead bag 180 will cause patient-support surface 56 toretain its shape against the contours of the patient's body.

If the surgical procedure to be performed on the patient requires thepatient's temperature to be reduced, an instruction can be providedthrough key pad 378 that will cause the temperature of thermal pad 260to decrease, withdrawing heat from patient-support surface 56 untilpatient-support surface 56 is at the desired temperature. If, during thecourse of the procedure, the patient is to be repositioned, rather thanhaving members of the surgical team manually reposition the patient andstuff wedges, rolled-up towels, or other objects under the patient tokeep patient at the new position, and then removing those objectsafterward, an instruction can be provided through key pad 378 that willactivate selected portions of bladder pad 140 to reposition the patient.Once the procedure is complete, the selected portions of bladder pad 140can be deactivated to return the patient to the desired position.

Body pad section 34 includes cover 86 and pad core elements 92 asillustratively shown in FIG. 4a. Although FIG. 4a illustratively showsbody pad section 34, the description below with respect to body padsection 34 applies generally to each pad section 30 and to pad coreelements 92 of each pad section 30. As such, the description below withrespect to body pad section 34 is to be taken as descriptive of eachpreferred pad section 30 and pad core elements 92 unless specificallystated otherwise.

Pad core elements 92 of body pad section 34 preferably include fire sock130 received in interior region 88 of cover 86 and defining an interiorregion 132 surrounding the other pad core elements 92 as shown in FIG.4a. Certain regulating authorities require articles such as surface padsystem 20 to be self-extinguishing and including fire sock 130 improvesthe self-extinguishing characteristics of pad core elements 92.Preferred fire sock 130 is made from FIREGARD® SENTRYSAK™ material madeby Spring Industries, Inc.

Pad core elements 92 of body pad section 34 also illustratively includehigh density base foam support layer 110 which is preferably positionedat the bottom of pad core 90 as illustratively shown in FIG. 4a. Supportlayer 110 is preferably a thermally active shock absorbing polyestervisco-elastic foam such as model number SAF50 50 foam produced by FritzNauer Limited of Switzerland. Support layer 110 forms a foundation ofpad core 90 and body pad section 34 providing support for pad coreelements 92 positioned to lie on top surface 112 of support layer 110.

If desired, top surface 112 of high density foam support layer 110 canbe shaped as shown in FIG. 2 for second arm pad section 44, to contourtop surface 48 of body pad section 34. As can be seen, each pad coreelement 92 that rests upon support layer 110 initially assumes thegeneral shape of top surface 112 of support layer 110, as shown in FIGS.2 and 3.

Preferred support layer 110 is formed from thermally active viscoelasticfoam as mentioned above. Visco-elastic foam is formulated so that thefirmness and support characteristics of the foam vary with thetemperature of the foam, unlike conventional foam which maintains agenerally constant durometer hardness and which provides the samesupport and firmness characteristics at each operating temperature. Thepreferred visco-elastic foam of support layer 110 is softer and morepliable at warmer temperatures and is firmer and tends to retain itsshape at cooler temperatures. Thus, support layer 110 will easilyconform to the shape of the patient carried on patient-support surface56 at warmer temperatures, and if subsequently cooled, will tend toretain its shape even after the patient is removed from patient-supportsurface 56 or when the position of the patient on patient-supportsurface 56 is temporarily changed.

Support layer 110 is preferably sculptured from a unitary foam piece toshape support layer 110 for use in pad sections 30. Support layer 110 ofbody pad section 34 is illustratively shaped as shown in FIG. 4a andincludes small cutouts 114 and a cavity 116. Cutouts 114 are configuredto receive valves and couplings that couple pad sections 30 together sothat these valves and couplings do not interfere with the support andfirmness characteristics of patient-support surface 56. Cavity 116provides the surgical team with access to the patient as needed forcertain medical procedures. If desired, top surface 112 of support layer110 can also be shaped without exceeding the scope of the invention aspresently perceived, for example, to include a cavity such as anelongated and transversely-extending trough adjacent to the heels of thepatient to reduce interface pressure between patient-support surface 56and the heels of the patient.

Although preferred support layer 110 is sculptured from a unitary blockof visco-elastic foam, it is within the scope of the invention aspresently perceived to form support layer 110 from a plurality of foamblocks. For example, support layer 110 can include foam blocks havingrelatively plush support and firmness characteristics adjacent to theheel of the patient on patient-support surface 56 to minimize pressureulcers on the heels of the patient.

Pad core elements 92 of body pad section 34 also illustratively includebladder pad 140 as shown in FIGS. 4a and 4 c. Bladder pad 140 includesan upwardly-facing top sheet 142 and a downwardly-facing bottom sheet144 engaging top surface 112 of high density foam layer 110. A pluralityof bladders 146 are appended to top surface 142 and are strategicallypositioned to provide adjustable firmness and support characteristicsfor the patient on patient-support surface 56 when bladders 146 areinflated and deflated.

Bottom sheet 144 is appended to top sheet 142 of bladder pad 140 andcooperates therewith to define a plurality of channels 148 of a channelsystem 150 beneath top sheet 142 as shown best in FIG. 4c. Bladder pad140 also includes a plurality of connectors 152 that are in fluidcommunication with the source of pressurized fluid 374. Connectors 152are in fluid communication with channels 148 of channel system 150. Eachbladder 146 is formed to include an interior region 156 and each channel148 is in fluid communication with interior region 156 of at least oneof bladders 146. Thus, channels 148 of channel system 150 are integrallyappended to bladder pad 140 and eliminate the need to include a seriesof hoses or other fluid impermeable conduits for bringing connectors 152into fluid communication with interior regions 156 of bladders 146.

Top sheet 142 of bladder pad 140 is formed to include an opening (notshown) extending therethrough. Bladder 146 is appended to top sheet 142and is formed to include an opening (not shown) in fluid communicationwith the opening of top sheet 142 so that the opening of top sheet 142is in fluid communication with interior region 156 of bladder 146. Theopening of top sheet 142 is also in fluid communication with one of thechannels 148 of channel system 150 so that pressurized fluid received inthe channel is communicated to interior region 156 of bladder 146through the opening in top sheet 142 and the opening in bladder 146 toinflate bladder 146. Likewise, pressurized fluid in interior region 156of bladder 146 can be communicated to the channel through the opening ofbladder 146 and the opening of top sheet 142 when bladder 146 is beingdeflated.

Including bladders 146 as a pad core element 92 of surface pad system 20allows the surgical team to maximize the surface area of contact betweenthe patient and patient-support surface 56, thereby minimizing thepressure of high interface pressure points between patient-supportsurface 56 and the patient, thus minimizing the possibility of formingpressure ulcers, neuropathy, or other disorders or conditions resultingfrom prolonged exposure to high interface pressure between patient andpatient-support surface 56. In addition, including bladders 146 in padsections 30 allows the surgical team to manipulate the position of thepatient on patient-support surface 56 without undertaking the arduoustask of manually repositioning the anesthetized patient andsimultaneously stuffing a log of foam, a log of gel, a rolled-up towel,or another object underneath the anesthetized and manually positionedpatient to hold the patient in the newly desired position. Instead, tomanipulate the position of the patient on patient-support surface 56 ofsurface pad system 20 in accordance with the present invention, thesurgical team needs to merely inflate or deflate a desired bladder 146,as described in more detailed hereinafter.

Illustrative and preferred bladder pad 140 is of unitary constructionand is made from nylon mesh reinforced polyurethane. Illustrativebladder pad 140 is made from the 13 mil (0.33 mm) thick supportedpolyurethane film produced by Cooley Inc., of Pawtucket, R.I. Channelsystem 150 can be formed by R.F. welding bottom sheet 144 to top sheet142. A free-flow connector 152 is preferably added to ends of eachchannel 148 to keep the channel open so that pressurized fluid can flowtherethrough.

Pad core elements 92 of body pad section 34 also illustratively includevacuum bead bag 180 which is received in interior region 88 of cover 86and is positioned to lie on top of bladder pad 140 as shown in FIGS. 4aand 4 b. Vacuum bead bag 180 includes an outer casing 182 defining aninterior region 184 in fluid communication with vacuum source 376through fittings 196 and vacuum conduit 68. Thus, the atmosphere ininterior region 184 of casing 182 can be evacuated by vacuum source 376or can be replaced through fittings 196 and conduit 68.

Interior region 184 of vacuum bead bag 180 receives a lower layer 186 ofcompressible beads 194 and an upper layer 188 of compressible beads 194as shown best in FIGS. 4a, 4 b, and 7. Lower and upper layers 186, 188each includes a plurality of elongated tubes 190 and each tube 190 ismade from a flexible material defining an interior region 192 of tube190 as shown best in FIG. 7.

Flexible tubes 190 are preferably made from a nylon mesh material havingan opening size that is small enough to contain compressible beads 194within interior regions 192 of tubes 190 while allowing the passage ofthe air or other gas comprising the atmosphere inside of interior region184 of vacuum bead bag 180 therethrough. Although in preferredembodiments elongated tubes 190 are made from nylon mesh, anysemipermeable material having an opening size small enough to containcompressible beads 194 therein while allowing the free passagetherethrough of air or any other gas comprising the atmosphere ofinterior region 184 of vacuum bead bag 180 can be used without exceedingthe scope of the invention as presently perceived.

In preferred embodiments, compressible beads 194 are white polystyrenebeads made by Huntsman Chemical Corporation of Chesapeake, Va. and thebeads preferably have a diameter between 1.5 and 2.5 mm (0.06-0.1inches). Preferably, the polystyrene beads 194 are allowed to outgas(air out) prior to incorporation into surface pad system 20 inaccordance with the present invention so that beads 194 are firmer thanpolystyrene beads that have not outgassed. Although preferred beads 194are made from polystyrene, it is within the scope of the invention aspresently perceived to provide beads 194 for vacuum bead bag 180 madefrom any compressible material that will allow beads 194 to deform asdescribed below with reference to FIG. 7.

Lower layer 186 of vacuum bead bag 180 includes a plurality oflongitudinally-extending tubes 190, each tube 190 being filled withcompressible beads 194 as shown, for example, in FIG. 7 and each tube190 extending in a direction generally parallel to the direction thateach other tube 190 of lower layer 186 extends as shown in FIG. 4b.Upper layer 188 of vacuum bead bag 180 also includes a plurality oftubes 190. Tubes 190 of upper layer 188 extend in a transversedirection, each tube 190 being filled with compressible beads 194 andeach tube 190 of upper layer 188 extending a direction generallyparallel to the direction that each other tube 190 of upper layer 188extends. Tubes 190 of upper layer 188 rest on top of tubes 190 of lowerlayer 186 as shown in FIGS. 4a, 4 b, and 7.

Vacuum bead bag 180 thus includes lower layer 186 having a plurality oftubes extending in one direction and upper layer 188 having a pluralityof tubes extending in a second direction. Preferably, the seconddirection is generally perpendicular to the first direction to providevacuum bead bag 180 with a “plywood effect.” The plywood effect of upperand lower layers 188, 186 provides increased strength and support tovacuum bead bag 180 when air is evacuated from interior region 184 andthus to patient-support surface 56 than would be provided by aconventional vacuum bead bag (not shown) having a single layer of beads.

Pad core elements 92 of body pad section 34 additionally includepressure reduction foam layer 220 which is received in interior region88 of cover 86 and is positioned to lie above and engaging vacuum beadbag 180 as shown in FIG. 4a. Pressure reduction foam layer 220 providespressure reduction to assist in reducing the pressure of high interfacepressure points between the patient and patient-support surface 56.

Illustrative and preferred pressure reduction foam layer 220 is madefrom a thermally active shock absorbing polyester foam that isformulated as a viscoelastic foam, Model No. SAF 65180 foam produced byFritz Nauer Limited of Switzerland. Thus, the support and firmnesscharacteristics of pressure reduction foam layer 220 varies with thetemperature of the foam in a manner similar to that described above withreference to support layer 110. Pressure reduction foam layer 220 issofter and more pliable at warmer temperatures and is firmer and tendsto retain its shape at cooler temperatures. Thus, pressure reductionfoam layer 220 will easily conform to the shape of the patient carriedon patient-support surface 56 at warmer temperatures, and ifsubsequently cooled, will tend to retain its shape even after thepatient is removed from patient-support surface 56 or when the positionof the patient or patient-support surface is temporarily changed.

In preferred embodiments, pressure reduction foam layer 220 issculptured from a unitary foam block to shape pressure reduction foamlayer 220 for use in pad sections 30. Pressure reduction foam layer 220of body pad section 34 is formed to include small cut-outs 222 forreceiving portions of couplings, fittings, or valves so that thecouplings, fittings, or valves do not interfere with the support andfirmness characteristics of pad sections 30. In addition, pressurereduction foam layer 220 is sculptured to include a cavity 224 which isconfigured to provide access to the surgical team to desired portions ofthe patient on patient-support surface 56 during selected medicalprocedures. If desired, pressure reduction foam layer 220 can also beshaped to include a cavity such as, for example, an elongated andtransversely-extending trough adjacent to the heels of the patient toreduce interface pressure between patient-support surface 56 and theheels of the patient without exceeding the scope of the invention aspresently perceived.

Although preferred pressure reduction foam layer 220 is sculptured froma unitary block of visco-elastic foam, it is within the scope ofinvention as presently perceived to form pressure reduction foam layer220 from a plurality of foam blocks. For example, pressure reductionfoam layer 220 can include foam blocks having relatively plush supportand firmness characteristics adjacent to the heel of the patient onpatient-support surface 56 to minimize pressure ulcers on the heels ofthe patient.

Pad core elements 92 of body pad section 34 additionally include athermal pad 260 received in interior region 88 of cover 86 andpositioned to lie on top of pressure reduction foam layer 220 as shownin FIG. 4a. Thermal pad 260 includes a top sheet 262 that cooperateswith a bottom sheet 264 to define a generally longitudinally-extendingserpentine-shape channel 266 therebetween. Illustrative and preferredtop and bottom sheets 262, 264 are made from nylon mesh reinforcedurethane sheets such as the 13 mil (0.33 mm) thick supportedpolyurethane film produced by Cooley Inc., of Pawtucket, R.I. Top sheet262 and bottom sheet 264 are R.F. welded to form channel 266therebetween.

Thermoregulation fluid is received in channel 266 and is circulatedbetween channel 266 of thermal pad 260 and heat exchanger 372 that ishoused within control housing 74 for controlling the temperature ofthermoregulation fluid in channel 266. Heat exchanger 372 controls thetemperature of the thermoregulation fluid circulating through channel266 so that thermal pad 260 can heat or cool patient-support surface 56to a desired temperature selected by members of the surgical team.

As described above, thermal pad 260 is positioned to lie on top ofpressure reduction foam layer 220 which is above vacuum bead bag 180 andbladder pad 140 as shown in FIG. 4a. Pressure reduction foam layer 220is a thermal insulator that would impede the transfer of heat betweenthermal pad 260 and patient-support surface 56 if pressure reductionfoam layer 220 were interposed between thermal pad 260 andpatient-support surface 56 so that placing pressure reduction foam layer220 beneath thermal pad 260 removes this impediment to heat transfer.

In addition, as described above, inflation of bladders 146 maximizes thesurface area of contact between the patient and patient-support surface56. Maximizing the surface area of contact also maximizes the conductiveheat transfer between patient-support surface 56 and the patient.Placing thermal pad 260 above bladders 146 causes bladders 146 to pressthermal pad 260 upwardly toward top 96 of cover 86 to maximize theconductive heat transfer from thermal pad 260 to top 96 of cover 86 andthus to patient-support surface 56.

Pad core elements 92 of pad core 90 of illustrative body pad section 34also include gel pack 310 which is received in interior region 88 ofcover 86 and which is positioned to lie on top of thermal pad 260 asshown in FIG. 4a. Gel pack 310 includes a casing 312 receiving a viscousfluid 314. Viscous fluid 314 flows away high interface pressure pointsand toward low interface pressure points to buoy the patient onpatient-support surface 56 around high interface pressure pointsminimizing the interface pressure between the patient andpatient-support surface 56 at the high interface pressure points.

Casing 312 of preferred gel pack 310 is made from a light weighturethane having a thickness of 6 mils (0.15 mm) such as polyurethanefilm Model No. EXR-625FS, natural film, made by J. B. ElastometricsCorporation of North Hampton, Mass. In addition, illustrative andpreferred viscous fluid 314 is made from silicone-based polymer materialsuch as that used for prosthetic devices including Oasis fabricated byTRU-LIFE of Dublin, Ireland.

As described above, pad core elements 92 are received in interior region88 of cover 86 as shown in FIG. 4a. Preferred cover 86 is made from abi-directional stretch ticking material that unlike conventional tickingmaterials can stretch in both a longitudinal direction and in a lateraldirection. Use of the bi-directional stretch material allows cover 86 ofbody pad section 34 to move and bend without folding against itself. Thepreferred ticking material is a dual coated polyester including a net ofdual coated urethane such as Via Tex 2 material, Manufacturing QualityNo. T5793 made by Pen-Nyla of Nottingham, England.

Cover 86 is formed to include openings 330 allowing for the passage ofconduits 60 therethrough and is formed to include an opening (not shown)for allowing the passage of pad core 90 into and out of interior region88 of cover 86. A zipper 332 surrounds the opening for allowing thepassage of pad core 90 and the zipper can be opened and closed to openand close the opening as shown in FIG. 4a. Cover 86 is additionallyformed to include a flap 334 covering zipper 332. Flap 334 is appendedto a portion of cover 86 above zipper 332 and flap 334 attaches to aside of cover 86 below zipper 332 by hook-and-loop type fasteners 336.In addition, illustrative and preferred cover 86 also includeshook-and-loop type fasteners (not shown) fixed to bottom 94 of cover 86for attaching body pad section 34 to table-top 22 of the surgical table.

When a patient initially lies on body pad section 34, gel pack 310 willdeform having viscous fluid 314 flow within casing 312 away fromdownwardly projecting portions of the patient that result in highinterface pressure points between the patient and patient-supportsurface 56. This movement of viscous fluid 314 away from high interfacepressure points and toward lower pressure interface points operates toincrease the surface area of contact between the patient andpatient-support surface as shown in FIG. 5. In addition, both pressurereduction foam layer 220 and high density foam layer 110 will deform ina like manner to minimize the interface pressure at high interfacepressure points between the patient and patient-support surface 56.However, gaps 350 will typically still be found between the patient andthe patient-support surface and relatively high interface pressurepoints will still exists between the patient and patient-support surface56 as described below with reference to FIGS. 13a, 13 b, and 13 c.

As described above, support layer 110 and pressure reduction foam layer220 are both made from a thermally active visco-elastic foam that ismore pliable and more readily conforms to the shape of the patient atwarmer temperatures than it does at cooler temperatures. Thevisco-elastic foam of support layer 110 and pressure reduction foamlayer 220 cooperates with gel pack 310 to cause patient support surface56 to deform and move away from high interface pressure points betweenthe patient and patient-support surface 56, thereby increasing thesurface area of contact between the patient and patient-support surface56 and reducing the interface pressure at high interface pressure pointsbetween the patient and patient-support surface 56, particularly whenthe patient first enters patient-support surface 56 and the temperatureof patient-support surface 56 is warmer and enhancing the comfort of thepatient.

Once the patient is resting on patient-support surface 56 andvisco-elastic foam layers 110, 220 and gel pack 310 have reshaped inresponse to the weight of the patient, bladders 146 of bladder pad 140can be inflated as shown in FIG. 6. The inflation of bladders 146operates to press patient-support surface 56 upwardly against thepatient and into gaps 350 formed between the patient and patient-supportsurface 56, thereby minimizing the gaps therebetween. Minimizing gaps350 between the patient and patient-support surface 56 maximizes thesurface area of contact between the patient and patient-support surface56, thereby evenly distributing the weight of the patient acrosspatient-support surface 56 and minimizing the interface pressure of thehighest remaining interface pressure points between the patient andpatient-support surface 56. Maximizing the surface area of contactbetween the patient and patient-support surface 56 also maximizes theconductive heat transfer between the patient and patient-support surface56.

Inflating bladders 146 to press patient-support surface 56 against thepatient and thereby more evenly distribute the weight of the patientacross patient-support surface 56 also maximizes the efficacy of gelpack 310 as shown in FIG. 6. Before bladders 146 are inflated, as shownin FIG. 5, a top wall 316 of casing 312 is pressed against a bottom wall318 of casing 312 at several locations indicating that additional reliefof high interface pressure points is needed. Evenly distributing theweight of the patient across patient-support surface 56 by inflatingbladders 146 also operates to more evenly distribute viscous fluid 314across casing 312 of gel pack 310 to minimize the area of locations atwhich top wall 316 of casing 312 engages bottom wall 318 of casing 312.Minimizing the engagement between top wall 316 and bottom wall 318maximizes the effectiveness of gel pack 310 and minimizes the interfacepressure of the highest interface pressure points between the patientand patient-support surface 56.

Inflating bladders 146 also causes pad core elements 92 positionedbetween bladder pad 140 and patient-support surface 56, including vacuumbead bag 180, to conform to the shape of patient-support surface 56 asshown in FIG. 6. Once bladders 146 have been inflated, pushingpatient-support surface 56 against the contours of the surface of thepatient engaging patient-support surface 56 and filling gaps 350 thatwere initially formed between the patient and patient-support surface56, the air can be evacuated from interior region 184 of casing 182 ofvacuum bead bag 180.

Evacuating the air from vacuum bead bag 180 causes casing 182 tocompress and causes compressible beads 194 to compress against oneanother as shown best in FIG. 7. Compression of beads 194 against oneanother eliminates the ability of beads 194 to move with respect to oneanother thus causing vacuum bead bag 180 to rigidly assume the shapeheld by vacuum bead bag 180 when the air was evacuated from interiorregion 184 of casing 182. Vacuum bead bag 180 will thus rigidly retainthe shape conforming to the shape of patient-support surface 56 shown inFIG. 6 so long as the air remains evacuated from vacuum bead bag 180. Inaddition, by forming vacuum bead bag 180 to include lower layer 186having a plurality of longitudinally-extending tubes 190 and upper layer188 having a plurality of transversely extending elongated tubes 190results in the plywood effect in which vacuum bead bag 180 provides arigid support both in the longitudinal direction and in the transversedirection.

Once air is evacuated from vacuum bead bag 180, bladders 146 can bedeflated as shown in FIG. 8. Because vacuum bead bag 180 rigidly assumesthe shape that it had immediately before air was evacuated from interiorregion 84, and because vacuum bead bag 180 is positioned to lie ininterior region 88 of cover 86 on top of bladder pad 140 and bladders146, deflating bladders 146 does not effect the conformal fit achievedbetween the patient and patient-support surface 56. However, bydeflating bladders 146, the patient is more firmly and solidly supportedthan when the patient is resting on inflated bladders 146 which may actas resilient “balloons” allowing patient to vibrate or bounce.

Once the patient and surface pad system 20 are both properly positionedand configured as shown in FIG. 8, the patient can be anesthetized and,if desired, surface pad system 20 can be used to lower the temperatureof patient-support surface 56. As described above, thermoregulationfluid circulates between channels 266 of thermal pads 260 and heatexchanger 372 which is carried in control housing 74. The temperature ofthe thermoregulation fluid and, thus, of thermal pad 260 andpatient-support surface 56 is adjusted by adjusting the amount of heatadded or removed from the thermoregulation fluid by heat exchanger 372.The control of heat exchanger 372 is described in more detail below withreference to FIG. 14.

Preferably, heat exchanger 372 is a so-called “Peltier device” forheating and cooling the thermal regulation fluid and contains no freonor other regulated chlorofluorocarbons (CFCs) or other ozone depletingchemicals. In preferred embodiments, the thermoregulation fluid is waterwhich circulates between the Peltier device and the channels 266 ofthermal pads 260, although any generally inert fluid having suitableheat capacity and viscosity characteristics can be used as thethermoregulation fluid without exceeding the scope of the invention aspresently perceived.

Also in preferred embodiments, thermocouple 382 is received in gel pack310 and is carried within casing 312 along with viscous fluid 314. Thethermocouple measures the temperature of viscous fluid 314 of gel pack310 and provides a temperature input signal in response thereto. Thetemperature input signal is received by a controller 370 which iscarried in control housing 74 as shown diagrammatically in FIG. 14.Controller 370 receives the temperature input signal and provides a heatexchange output signal in response to the temperature input signal. Heatexchanger 372 receives the heat exchange output signal from thecontroller and adjusts the temperature of the thermoregulation fluiduntil the temperature input signal from the thermocouple indicates thatthe thermocouple has reached a desired temperature. It will beunderstood by those skilled in the art that although the temperatureinput signal indicates the temperature of viscous fluid 314 in gel pack310, the proximity of gel pack 310 to patient-support surface 56 makesmeasurement of the temperature of gel pack 310 an adequate estimate ofthe temperature of patient support surface 56 and the differencetherebetween can be adequately compensated for by controller 370.

Once the temperature of patient-support surface 56 and of the patienthave reached the desired temperature, the surgical procedure may begin.If desired, surface pad system 20 may be manipulated to reposition theanesthetized patient after the surgical procedure has started. Forexample, when performing a Cesarean section, it is a common practice forthe surgical team to place a roll, a wedge, or some other object underthe left hip of the mother to shift the weight of the baby by moving themother onto her right side. Rather than having members of the surgicalteam manually reposition the mother, surface pad system 20 in accordancewith the present invention can include a second side bladder 158positioned to lie on top of a first side bladder 160, both of which areappended to bladder pad 140 as shown in FIG. 9. When the surgical teamwishes to reposition the mother, a member of the surgical team maysimply provide a user input from keypad 378 to controller 370 which willactivate the source of pressurized fluid as well as valving of valvemanifold 384 necessary to direct the pressurized fluid to first andsecond side bladders 158, 160 to inflate side bladders 158, 160 as shownin FIG. 9.

Inflation of both side bladders 158, 160 operates to roll the patient toone side as shown in FIG. 9. It will be appreciated by those skilled inthe art that using surface pad system 20 in accordance with the presentinvention to reposition the patient is advantageous for the patient inthat a more controlled repositioning can occur than when members of thesurgical team manually reposition the patient. In addition,patient-support surface 56 grips the patient to firmly hold the patientin place relative to patient-support surface 56 and to prevent slippingof the patient with respect thereto during repositioning of the patientand patient-support surface 56. Once the baby is removed from themother, first and second side bladders 158, 160 may easily be deflatedto reposition patient-support surface 56 to the generally horizontalposition shown in FIG. 8.

In preferred embodiments, bladder pad 140 also includes a centralsupport bladder 162 extending longitudinally beneath the spine of thepatient on patient-support surface 56 as shown best in FIGS. 10 and 12.Central support bladder 162 can be inflated to a first pressure as shownin FIGS. 6 to press patient-support surface 56 against the patient tofill gaps 350 between the patient and patient-support surface 56 asdescribed above. In addition, central support bladder 162 can beinflated to a second pressure which is greater than the first pressureto inflate central support bladder 162 sufficiently to press the spineof the patient upwardly and hyperextend the chest of the patient asshown in FIG. 10. It will be appreciated by those skilled in the artthat use of surface pad system 20 to hyperextend the chest cavity of thepatient on patient-support surface 56 for certain surgical proceduressuch as cardiovascular procedures is preferable to the current practiceof placing a wedge, a rolled-up gel pack, a rolled-up towel, or otherobject beneath the anesthetized patient during the procedure. Inaddition, once the procedure is complete, rather than having to removethe object from underneath the anesthetized patient, use of surface padsystem 20 allows for a more controlled lowering of the patient by simplydeflating central support bladder 162.

Cover 86 can be formed to include first and second spaced-apartelongated pockets 338 positioned to lie adjacent to first side 38 ofbody pad section 34 and second side 40 of body pad section 34,respectively, as shown in FIG. 11. Pockets 338 can each contain bladders340 which are not connected to bladder pad 140, but which can beinflated to tilt patient-support surface 56 as shown in FIG. 11. It isadvantageous in certain surgical procedures to tilt table-top 22 of thesurgical table. Bladders 340 are particularly useful during suchprocedures for “fine-tuning” the orientation of patient-support surface56.

Illustrative and preferred surface pad system 20 includes pad sections30 containing bladder pads 140 having bladders 146 that are preferablyconfigured and positioned to lie as shown in FIG. 12 (in phantom)relative to the patient on patient-support surface 56. As describedabove, surface pad system 20 includes first side bladders 160 positionedto lie on both sides of the patient, at least one second side bladder158 positioned to lie above one of first side bladders 160, and centralsupport bladder 162 supporting the spine of the patient. In addition,bladders 146 include a lumbar bladder 164 supporting the lumbar regionof the patient's back, a sacrum bladder 166 supporting the sacrum of thepatient, and three leg-support bladders 168, one of which is positionedto lie between the legs of the patient and the others of which arepositioned to lie on the outsides of the legs of the patient.

Although illustrative and preferred surface pad system 20 includes sidebladders 158, 160, central support bladder 162, lumbar bladder 164,sacrum bladder 166, and leg support bladders 168 as described above withreference to FIG. 12, the shapes and portions of bladders 146 withinsurface pad system 20 relative to the patient can be varied withoutexceeding the scope of the invention as presently perceived. Forexample, bladders 146 can include a generally “doughnut-shaped” bladderfor supporting the head of the patient, the bladder being ring-shapedwith an opening formed therein so that the lowermost portion of the headof the patient is adjacent to the opening to minimize the interfacepressure against the patient's head as well as to stabilize thepatient's head.

Use of surface pad system 20 in accordance with the present inventionminimizes the interface pressure of the high interface pressure pointsbetween the patient and patient-support surface 56 as showndiagrammatically in FIGS. 13a, 13 b, and 13 c. Each of FIGS. 13a, 13 band 13 c are diagrammatic representations indicating the interfacepressure between the patient and patient-support surface 56. Eachdiagram includes dots 380 the density of which indicates the magnitudeof the interface pressure between the patient and patient-supportsurface 56. Portions in each of FIGS. 13a, 13 b, and 13 c showing a highdensity of dots 380 indicate high interface pressures between thepatient and patient-support surface 56 on those portions ofpatient-support surface 56. Likewise, portions of FIGS. 13a, 13 b, and13 c showing a low density of dots 380 or no dots 380 indicates lowinterface pressures between the patient and patient-support surface 56or even no interface pressure therebetween indicating that the patientdoes not engage those portions of patient support surface 56.

The weight of a patient supported on a conventional surface cover for asurgical table is supported primarily by the head, shoulder blades,sacrum, and heels of the patient as shown diagrammatically in FIG. 13a.The above-noted portions of the patient are the downwardly extendingextremities of the patient when resting on a conventional surface coverfor a surgical table and, as a result, these extremities of the patientsupport most of the weight of the patient and experience the highestinterface pressure between the patient and patient-support surface 56.It can also be seen in FIG. 13a that several portions of the patienthave low interface pressures against patient-support surface 56 and evenno contact with patient-support surface 56 as indicated by portions ofFIG. 13a having no dots 380 associated therewith. Thus, it can be seenthat the weight of the patient is not evenly distributed across theconventional surface cover for a surgical table.

When the patient rests on patient-support surface 56 of surface padsystem 20 in accordance with the present invention as shown in FIG. 5before bladders 146 are inflated and before air is evacuated frominterior region 184 of vacuum bead bag 180, high density foam layer 110and pressure reduction foam layer 220, both of which are made ofthermally active visco-elastic foam, cooperate with gel pack 310 todistribute the weight of the patient across patient-support surface 56as shown diagrammatically in FIG. 13b. As can be seen, the high densityof dots near the patient's head, shoulder blades, sacrum, and heelsindicate that although the weight of the patient is more evenlydistributed across patient-support surface 56 than is distributed withthe conventional surface covering for a surgical table shown in FIG.13a, there are still some relatively high interface pressure pointsbetween the patient and patient-support surface 56.

As indicated above with respect to FIG. 6, inflating bladders 146 causespatient-support surface 56 to conformingly engage the patient and tomaximize the surface area of engagement between the patient andpatient-support surface 56, thereby minimizing the occurrence of highinterface pressure points between the patient and patient-supportsurface 56 as shown diagrammatically in FIG. 13c. By minimizing thesehigh interface pressure points between the patient and patient-supportsurface 56, use of surface pad system 20 in accordance with the presentinvention minimizes pressure ulcers, neuropathy, and other nervedisorders and damage to nerve bundles that can result from prolongedexposure to high interface pressures.

In addition, as described above, surface pad system 20 allows thesurgical team to manipulate and adjust the temperature ofpatient-support surface 56 and thus of the patient. The use of bladders146 to press patient-support surface 56 into conforming engagement withthe patient and the placement of thermal pad 260 above bladder pad 140so that thermal pad is likewise pressed upwardly toward the patient,operates to maximize the heat transfer between thermal pad 260 and thepatient through gel pack 310 and top 96 of cover 86.

Surface pad system 20 also allows for an automated and controlledpositioning of the patient relative to table-top 22 of the surgicaltable while enhancing the stability of the patient during repositioningoperations. Instead of having members of the surgical team manuallyrepositioning the anesthetized patient and simultaneously trying tobolster the patient in the new position using wedges, pillows, or otherobjects that are shoved between the patient and the tops of conventionalcoverings, surface pad system 20 automatically and controllablyrepositions the patient when instructed to do so by a member of thesurgical team simply by inflating or deflating bladders 146 as required.Use of internal bladders 146 to reposition the patient eliminates theneed to use rolled-up towels, pillows, or other objects to support thepatient in the new position. These objects, which are placed between thepatient and patient-support surface 56, are typically thermalinsulators, so that elimination of the use of these objects eliminatesan impediment to the heat transfer between patient-support surface 56and the patient.

As described above, surface pad system 20 in accordance with the presentinvention includes control housing 74 which contains the controller 370,the heat exchanger 372, the pressurized fluid source 374, vacuum source376, and a valve manifold 384 as shown diagrammatically in FIG. 14.Controller 370 receives the user input signals from key pad 378 and thetemperature input signal as described above from thermocouple 382positioned in gel pack 310 of body pad section 34. In addition,controller 370 receives temperature input signals from thermocouples 382positioned in gel packs 310 of each pad section 30 that include thermalpads 260. Controller 370 receives the user input signals and thetemperature input signals and provides a heat exchange output signal toheat exchanger 372, a vacuum output signal to vacuum source 376, apressurized fluid output signal to the pressurized fluid source 374, anda valve positioning signal to valve manifold 384 in response thereto.

Heat exchanger 372 operates to heat and cool the circulatingthermoregulation fluid in response to the heat exchanger output signalin order to maintain the temperature of thermocouples 382 at the desiredtemperature. In preferred embodiments, channels 266 of thermal pads 260of all pad sections 30 are coupled together and are in fluidcommunication with one another through thermoregulation fluid supplyconduit 62 and thermoregulation fluid return conduit 64. Thus,thermoregulation fluid flows from heat exchanger 372, through each padsection 30 in series, then back to heat exchanger 372. Consequently, oneheat exchanger 372 can control the temperature of thermal pads 260 ofeach pad section 30.

Vacuum source 376 operates to evacuate the atmosphere from interiorregion 184 of vacuum bead bags 180 or to allow air or another generallyinert gas to flow into interior region 184 of vacuum bead bag 80 throughconduits 68 in response to the vacuum output signal from controller 370.In preferred embodiments, interior regions 184 of vacuum bead bags 180of all pad sections 30 are coupled together and are in fluidcommunication with one another through vacuum conduit 68. Thus, when airis evacuated from conduit 68, air flows from each interior region 184,through conduit 68, to vacuum source 376 forcing compressible beads 194to squeeze against each other and deform, thereby becoming immobile withrespect to one another and forcing vacuum bead bag 180 to its rigidcondition. Likewise, when air is permitted to return to interior regions184, the air flows from vacuum source 376, through conduit 68, tointerior regions 184 allowing vacuum bead bags 180 to once again becomepliable.

Pressurized fluid source 374 operates to supply pressurized fluid toselected bladders 146 at a pressure in accordance with the pressurizedoutput signal and the valve positioning signal from controller 370 or toallow pressurized fluid to escape from selected bladders 146 in responseto the pressurized fluid output signal and the valve positioning signalfrom controller 370. In preferred embodiments, valve manifold 384includes a plurality of valves (not shown), including a valve (notshown) associated with each pressurized fluid conduit 60 which isassociated with each bladder 146. When a user input signal requires oneof the bladders 146 to inflate, pressurized fluid source 374 providespressurized fluid to valve manifold 384 and the valve associated withthe selected bladder 146 opens so that pressurized fluid can flow alongconduit 66 associated with the selected bladder 146 to fill and inflatethe selected bladder 146. When a user input signal requires one of thebladders 146 to deflate, pressurized fluid is removed from valvemanifold 384 and the valve associated with the selected bladder opens sothat pressurized fluid can flow along conduit 66 associated with theselected bladder 146 from the selected bladder 146 to valve manifold384, thereby allowing the selected bladder 146 to deflate.

It will be appreciated by those skilled in the art that use of valvemanifold 384 allows surface pad system 20 to include only one source ofpressurized fluid 374 to service all bladders 146 rather than requiringa separate source of pressurized fluid for each bladder 146. Asmentioned above, the preferred pressurized fluid is air, although anygenerally inert fluid such as nitrogen, water, or any other suitableliquid or gas can be used as the pressurized fluid to inflate bladders146. It is therefore within the scope of the invention as presentlyperceived for the source of pressurized fluid to include an air or watertank, an air compressor, a “house” compressed air or other compressedgas line, a water line of a hospital or other facility, or any othersuitable source of pressurized fluid.

Having each of vacuum bead bag 180, bladders 146, and thermal pad 260controlled by controller 370 provides a convenient single source ofinformation for data logging parameters such as the amount of time apatient spends in a single position, the amount of time a patient spendson surface pad system 20 and thus on table-top 22 of the surgical table,the amount of time the patient spends at a particular temperature, andother parameters related to the operation of surface pad system 20. Inaddition, controller 370 can coordinate the operation of bladders 146,vacuum bead bag 180, and thermal pad 260, for example, to control thesequence of operations such as providing that bladders 146 inflatebefore air is evacuated from interior region 184 of vacuum bead bag 180,providing that the air is evacuated from bladders 146 before thetemperature of the patient is reduced for surgery, as well as providingcomputer control for such tasks as controlling the temperature of thepatient and patient-support surface 56 for surgical procedures performedat reduced temperatures. If desired, controller 370 can also beprogrammed to automatically adjust bladders 146, vacuum bead bag 180,and thermal pad 260.

Although illustrative surface pad system 20 includes head pad section32, body pad section 34, leg pad section 36, first arm pad section 42,and second arm pad section 44, the number of pad sections 30 and thearrangement of pad sections 30 can be varied without exceeding the scopeof the invention as presently perceived. For example, head pad section32 can be eliminated from surface pad system 20 and can be replaced witha conventional head pad for a surgical surface such as a“doughnut-shaped” pad commonly used to support the head of a patient.For another example, if desired, surface pad system 20 can include anadditional pad section (not shown) that is positioned to lie betweenbody pad section 34 and leg pad section 36.

In illustrative and preferred surface pad system 20, pad sections 30 areremovably coupled to one another so that each pad section 30 can operateindependently of the other pad sections 30. Conduits 60 are providedwith quick disconnect couplings 72 as shown in FIG. 1 to facilitatedisconnecting one of pad sections 30 from another of pad sections 30 andreconnecting to yet another of pad sections 30 or to couplings 62 ofhose 76. For example, surface pad system 20 can be operated using bodypad section 34, leg pad section 36, and arm pad sections 42, 44, havingthe head of the patient resting on a conventional pillow. For anotherexample, surface pad system 20 can be operated using only body padsection 34 and leg pad section 36 with the head of the patient supportedby a conventional pillow and the arms of the patient resting ontable-top 22 or on top of the patient. As can be seen, the specificconfiguration or number of pad sections 30 of surface pad system 20 canbe varied without exceeding the scope of the invention as presentlyperceived.

Although the invention has been described in detail with reference to apreferred embodiment, additional variations and modifications existwithin the scope and spirit of the invention as described and defined inthe following claims.

What is claimed is:
 1. A surface pad system for supporting a patient ona surgical table, the surface pad system comprising: a cover defining aninterior region, a foam layer received in the interior region, the foamlayer being made from a thermally active visco-elastic foam having alower indention load deflection when the foam is warmer and a higherindention load deflection when the foam is cooler so that the surfacepad system readily conforms to the patient at warmer temperatures andretains its shape at lower temperatures, and a temperature controllerconfigured to adjust the temperature of the foam layer.
 2. The surfacepad system of claim 1, wherein the foam layer is elongated and is formedto include an upwardly-facing top surface, the top surface being concaveso that the foam layer and the cover cooperate to definelongitudinally-extending spaced-apart ridges and alongitudinally-extending trough therebetween.
 3. The surface pad systemof claim 1, wherein the foam layer is formed to include a plurality ofcutouts.
 4. The surface pad system of claim 1, wherein the foam layer isformed to include a cavity configured to provide access to a portion ofthe patient during a medical procedure.
 5. The surface pad system ofclaim 1, wherein the cover is made from a material that is stretchablefrom a first length to a second length which is longer than the firstlength in a first direction and that is stretchable from a third lengthto a fourth length which is longer than the third length in a seconddirection, the second direction being generally perpendicular to thefirst direction.
 6. The surface pad system of claim 1, furthercomprising a needle receptacle positioned to lie adjacent to the cover,the needle receptacle including an outer shell that is formed to includean opening configured to receive a needle.
 7. The surface pad system ofclaim 1, further comprising a layer of cut-proof material positioned tolie between a top surface of the cover and the foam layer so that thefoam layer is protected against penetration by a sharp object thatpenetrates the top surface of the cover.
 8. The surface pad system ofclaim 1, further comprising at least one bladder which is inflatable tomove a top surface of the cover upwardly toward the patient to minimizegaps between the patient and the top surface and to distribute thepatient's weight across the top surface so that an interface pressurebetween the patient and the top surface is minimized.
 9. A surface padsystem for supporting a patient on a surgical table, the surface padsystem comprising: a cover defining an interior region, a foam layerreceived in the interior region, the foam layer being made from athermally active visco-elastic foam having a lower indention loaddeflection when the foam is warmer and a higher indention loaddeflection when the foam is cooler so that the surface pad systemreadily conforms to the patient at warmer temperatures and retains itsshape at lower temperatures, and a thermal pad received in the interiorregion and positioned adjacent the foam layer.
 10. A surface pad systemfor supporting a patient on a surgical table, the surface pad systemcomprising: a cover defining an interior region, a foam layer receivedin the interior region, the foam layer being made from a thermallyactive visco-elastic foam having a lower indention load deflection whenthe foam is warmer and a higher indention load deflection when the foamis cooler so that the surface pad system readily conforms to the patientat warmer temperatures and retains its shape at lower temperatures, andat least one of a vacuum bead bag, an inflatable bladder, and a gel packlocated within the interior region of the cover.
 11. A surface padsystem for supporting a patient on a surgical table, the surface padsystem comprising: a cover defining an interior region, a foam layerreceived in the interior region, the foam layer being made from athermally active visco-elastic foam having a lower indention loaddeflection when the foam is warmer and a higher indention loaddeflection when the foam is cooler so that the surface pad systemreadily conforms to the patient at warmer temperatures and retains itsshape at lower temperatures, a thermal pad received in the interiorregion of the cover, a heat exchanger coupled to the thermal pad, thethermal pad including a channel in fluid communication with the heatexchanger and configured to receive a thermoregulation fluid therefrom,and a controller coupled to the heat exchanger to control thetemperature of the thermoregulation fluid, thereby controlling thetemperature of a patient-support surface.
 12. A surface pad system for asurgical table, the surface pad system comprising: at least two padsections, each pad section including a pad core, at least one of the padsections being configured to move relative to the other pad section, anda cover defining an interior region configured to receive the at leasttwo pad sections, the cover being made from a material that isstretchable from a first length to a second length which is longer thanthe first length in a first direction and that is stretchable from athird length to a fourth length which is longer than the third length ina second direction, the second direction being generally perpendicularto the first direction, and being configured to stretch in response tothe one pad section being moved relative to the other pad section. 13.The surface pad system of claim 12, wherein the cover is made from aliquid impermeable material to protect the pad sections from liquidsfrom outside of the surface pad system and to prevent the escape ofliquids from the interior region of the cover.
 14. The surface padsystem of claim 12, further comprising a foam layer received in theinterior region of the cover, the foam layer being made from a thermallyactive visco-elastic foam having a lower indention load deflection whenthe foam is warmer and a higher indention load deflection when the foamis cooler so that the surface pad system readily conforms to the patientat warmer temperatures and retains its shape at lower temperatures. 15.The surface pad system of claim 14, further comprising a layer ofcut-proof material positioned to lie between a top surface of the coverand the foam layer so that the foam layer is protected againstpenetration by a sharp object that penetrates the top surface of thecover.
 16. The surface pad system of claim 12, further comprising aneedle receptacle positioned to lie adjacent to the cover, the needlereceptacle including an outer shell that is formed to include an openingconfigured to receive a needle.
 17. The surface pad system of claim 12,wherein the pad core includes at least one bladder which is inflatableto move a portion of the pad core and a top surface of the coverupwardly toward the patient to minimize gaps between the patient and thetop surface and to distribute the patient's weight across the topsurface so that an interface pressure between the patient and the topsurface is minimized.
 18. The surface pad system of claim 12, furthercomprising a thermal pad received in the interior region of the cover,and a heat exchanger coupled to the thermal pad, the thermal padincluding a channel in fluid communication with the heat exchanger andconfigured to receive a thermoregulation fluid therefrom, and furthercomprising a controller being coupled to the heat exchanger to controlthe temperature of the thermoregulation fluid, thereby controlling thetemperature of a patient-support surface.
 19. A surface pad system for asurgical table, the surface pad system comprising: a pad core, a coverdefining an interior region configured to receive the pad core, thecover being made from a material that is stretchable from a first lengthto a second length which is longer than the first length in a firstdirection and that is stretchable from a third length to a fourth lengthwhich is longer than the third length in a second direction, the seconddirection being generally perpendicular to the first direction, and atleast one of a vacuum bead bag, an inflatable bladder, and a gel packlocated within the interior region of the cover.
 20. A method forsupporting a patient on a surface pad system of a surgical table,comprising the steps of: providing a cover defining an interior region,placing a foam layer in the interior region of the cover, the foam layerbeing made from a thermally active visco-elastic foam having a lowerindention load deflection when the foam is warmer and a higher indentionload deflection when the foam is cooler so that the surface pad systemreadily conforms to the patient at warmer temperatures and retains itsshape at lower temperatures, providing at least one bladder which isinflatable to move a top surface of the cover upwardly toward thepatient, and selectively inflating the at least one bladder to minimizegaps between the patient and the top surface and to distribute thepatient's weight across the top surface so that an interface pressurebetween the patient and the top surface is minimized.
 21. The method ofclaim 20, further comprising the step of repositioning the patient byinflating the at least one bladder.
 22. The method of claim 21, furthercomprising the step of repositioning the patient by deflating the atleast one bladder.
 23. The method of claim 20, further comprising thesteps of: providing a vacuum bead bag within the interior region of thecover, conforming the vacuum bead bag to the contours of the patient,and retaining the shape of the vacuum bead bag by evacuating air fromthe vacuum bead bag.
 24. The method of claim 23, wherein the vacuum beadbag includes a casing and a plurality of compressible beads positionedwithin the casing and wherein the shape of the vacuum bead bag isretained due to the compression of the plurality of compressible beadsand due to a plurality of longitudinally extending tubes on a lowerlayer of the vacuum bead bag and a plurality of transversely extendingtubes on an upper layer of the vacuum bead bag.
 25. The method of claim23, further comprising the step of deflating the at least one bladder toprovide a rigid support for the patient.
 26. The method of claim 23,further comprising the step of lowering the temperature of the foamlayer.
 27. The method of claim 20, wherein the temperature of the foamlayer is adjusted by a thermal pad received in the interior region. 28.The method of claim 27, further comprising the step of providing a heatexchanger in fluid communication with a channel in the thermal pad. 29.The method of claim 28, wherein a thermoregulation fluid is provided tothe channel.
 30. The method of claim 29, further comprising the step ofproviding a controller coupled to the heat exchanger to control thetemperature of the thermoregulation fluid, thereby controlling thetemperature of a patient support surface.
 31. The method of claim 20,further comprising the step of adjusting the temperature of the foamlayer.